Chapter 1.2: Types and Components of Computer Systems

Central Processing Unit (CPU)

• The CPU is the 'brain' of the computer where searching, sorting, calculating, and decision-making occur.
• CPU speed is measured in Gigahertz (GHz).
• 1 GHz CPU can carry out 1 billion instructions per second.
• Popular CPU brands: Intel and AMD.

Main Memory

• CPU checks Cache for data; if not found, it checks RAM.
• Temporary data from applications in use is held in Main Memory.
• Applications are installed in Secondary Storage (Hard drive).

Cache

• Fastest type of memory.
• Located between the processor and RAM.
• Collects data from RAM and holds commonly used data.
• Automatically transfers the next set of data from RAM for CPU processing.

RAM (Random Access Memory)

• Temporarily stores instructions the computer is running while data is being processed by the CPU.
• Volatile: data is lost when the computer is turned off.

ROM (Read Only Memory)

• Built-in memory that cannot be changed.
• Holds ‘boot up’ instructions to start the computer.
• Non-volatile: memory is not lost when the computer is turned off.

Memory Differences

• Cache: Fastest, located between CPU and RAM, holds common data.
• RAM: Temporary data, volatile (data lost on startup).
• ROM: Read-only, bootup instructions, non-volatile (data not lost).

Input and Output Devices

• Peripheral devices connect to a computer for data input and output.
• Input devices: pass data into the computer.
• Output devices: take data from the computer.

Secondary/Backing Storage

• Non-volatile: Data is not lost when the computer is turned off.
• Stores data for a long time; data can be read from and written to.
• Users often make copies of original files on backing storage.